Abstract: In response to key operation, a portable terminal lights up an LCD unit, and also lights up keys only when it is dark around the portable phone by measuring external brightness.

Abstract: In response to key operation, a portable terminal lights up an LCD unit, and also lights up keys only when it is dark around the portable phone by measuring external brightness.

Abstract: An apparatus for detecting the coincidence of two input signals comprises a first unit for deciding elevation between two input signals, a second unit for connecting a low level signal selected from the input signals to one output path for the low level signal and connecting a high level signal selected from the input signals to another output path for the high level signal as determined by the decision output, a third unit for producing a tolerance level for deciding one input signal level is coincident with another input signal level, a fourth unit for adding the low level signal form the output path to the tolerance level, and a fifth unit for comparing the adding output with the high level signal from the output path, and deciding one input signal level is coincident with another input signal level if a level of the addition output is higher than a level of the high level signal.